Asbestos Fiber Concentrations Research Articles

Occupational exposure to chrysotile in an asbestos cement factory in Kyrgyzstan.

An increasing number of countries are banning the production and use of asbestos, in compliance with the ratification of the C162 Asbestos Convention and the Basel Convention, and in response to the call for its elimination in the ILO resolution and WHO reports on the health risks associated with asbestos. Nevertheless, several countries, including Kyrgyzstan, are still miners and/or manufacturers of asbestos. The main objective of the study is to assess the occupational exposure to chrysotile of workers engaged in a production facility of asbestos-cement products in Kyrgyzstan. Monitored workers (n = 16, for a total of n = 18 samples) were divided into 3 "Similar Exposure Groups" (SEGs; SEG-1: asbestos loading; SEG-2; asbestos-cement mixing; SEG-3: cutting of asbestos-cement sheets) according to EN 689 standard. Samples were collected through personal sampling and subsequently examined by means of scanning electron microscope equipped with an energy-dispersive spectrometer for the compositional analysis of each fibre. The numerical concentration of airborne asbestos fibres was henceforward determined by dividing the number of fibres and the volume of sampled air (expressed in the number of fibres per millilitre of air: ff/ml). Investigated workers resulted to be exposed to chrysotile fibres. Results (GM ± GSD) outlined extremely high exposure levels for SEG-1 (2.2±2.1 ff/ml) and SEG-3 (4.7±1.6 ff/ml) workers and lower-but still relevant-exposure values for SEG-2 (0.91±2.6 ff/ml) workers. The results obtained in this case study can help to document potentially critical situations of occupational exposure to asbestos that can still occur nowadays in low and middle-income countries where asbestos is still mined and processed.

Assessment of worst-case potential airborne asbestos exposure associated with the use of cosmetic talc: application of an exponential decay model.

Talc is used in cosmetic products to confer desirable properties, such as moisture absorption and smooth texture, to the finished products. Concerns have been raised about the potential presence of asbestos in products containing cosmetic talc. Reconstruction of potential asbestos exposure from the use of cosmetic talc products (assuming a trace level of asbestos) requires consideration of consumer use patterns. Although application generally only lasts seconds, exposure theoretically may continue if the consumer remains in the immediate vicinity. Most published exposure measurements have not adequately characterized the potential for continued exposure. In this analysis, estimates and measurements of airborne asbestos fiber concentrations associated with cosmetic talc use from 10 published studies were used as inputs to an exponential decay model to estimate "worst-case" exposure during and following application. The resulting geometric mean 30-min time-weighted average (TWA) concentrations were 0.006 f/cc for both puff and shaker application, for diapering, 0.0001f/cc (adult applying baby powder) and 0.0002 f/cc (infant), and for makeup application, 0.0005 f/cc. Application of an exponential decay model to measured or estimated asbestos concentrations associated with the use of cosmetic talc products yields a conservative means to comprehensively reconstruct such exposures. Moreover, our results support that, if a cosmetic talc powder product contained a trace level of asbestos fibers, the "worst-case" airborne asbestos exposure associated with its application is low.

A postmortem case control study of asbestos burden in lungs of malignant mesothelioma cases

BackgroundAsbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends.MethodsAsbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM–EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023.ResultsAsbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011.DiscussionThe results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011.

Asbestos burden in lungs of non-occupationally exposed women from Broni (Pavia, Italy): a postmortem SEM-EDS study.

In Italy the incidence of malignant mesothelioma (MM) among women is remarkably high, due to the several contexts in which women had been exposed to asbestos. However, very few studies in literature focus on the inorganic lung content in women. The aim of this retrospective, observational study is to investigate the asbestos lung burden, in terms of concentration, dimensions and type of asbestos, in 42 women who died from MM and had been non-occupationally exposed to asbestos during the activity of the asbestos-cement plant located in Broni (Pavia, Northern Italy) where mainly chrysotile, crocidolite and amosite were used. Lung samples taken during forensic autopsies have been digested using sodium hypochlorite and filtered through a cellulose-ester membrane. The filter was examined using a scanning electron microscope and the chemical composition of the fibers was analyzed using an electron dispersive spectroscopy. The number of detected inorganic fibers, asbestos fibers and asbestos bodies (ABs) were normalized to 1 gram of dry tissue. In six samples no asbestos has been detected. Overall, the most represented kind of asbestos was amosite, followed by crocidolite, tremolite/actinolite asbestos and chrysotile. The concentration of all inorganic fibers was significantly higher in women with environmental and household exposures compared with those with only environmental exposure (P=0.025), as well as the concentration of asbestos fibers (P=0.019) and ABs (P=0.049). We found a significant correlation between the concentration of asbestos fibers and the duration of exposure (rho =0.413, P=0.008), as well as with the latency of MM (rho =0.427, P=0.005). The distance of the residential address from the factory and the time spent daily in contact with asbestos did not influence the lung asbestos burden. These results suggest the relevance of the lung clearance of asbestos, regarding mainly chrysotile. As a consequence, although scanning electron microscopy -energy dispersive X-ray spectroscopy (SEM-EDS) is considered the most reliable tool for assessing previous exposure to asbestos, its results should be interpreted with caution, especially in a legal context. In addition, our data confirm the relevance of environmental and household exposure in determining asbestos concentration in lungs and highlight the importance of household exposure.

Asbestos-Environment Pollution Characteristics and Health-Risk Assessment in Typical Asbestos-Mining Area.

Asbestos has been confirmed as a major pollutant in asbestos-mining areas that are located in western China. In general, asbestos-fibre dust will is released into the environment due to the effect of intensive industrial activities and improper environmental management, such that the health of residents in and around mining areas is jeopardised. A typical asbestos mining area served as an example in this study to analyse the content and fibre morphology of asbestos in soil and air samples in the mining area. The effects of asbestos pollution in and around the mining areas on human health were also assessed based on the U.S. Superfund Risk Assessment Framework in this study. As indicated by the results, different degrees of asbestos pollutions were present in the soil and air, and they were mainly concentrated in the mining area, the ore-dressing area, and the waste pile. The concentration of asbestos in the soil ranged from 0.3% to 91.92%, and the concentration of asbestos fibres in the air reached 0.008-0.145 f·cc-1. The results of the scanning-electron microscope (SEM) energy suggested that the asbestos was primarily strip-shaped, short columnar, and granular, and the asbestos morphology of the soils with higher degrees of pollution exhibited irregular strip-shaped fibre agglomeration. The excess lifetime cancer risk (ELCR) associated with the asbestos fibres in the air of the mining area was at an acceptable level (10-4-10-6), and 40.6% of the monitoring sites were subjected to unacceptable non-carcinogenic risks (HQ > 1). Moreover, the waste pile was the area with the highest non-carcinogenic risk, followed by the ore dressing area, a residential area, and a bare-land area in descending order. In the three scenarios of adult offices or residences in the mining area, adults' outdoor activities in the peripheral residence areas, and children's outdoor activities, the carcinogenic-and non-carcinogenic-risk-control values in the air reached 0.1438, 0.2225 and 0.1540 f·cc-1, and 0.0084, 0.0090 and 0.0090 f·cc-1, respectively. The results of this study will lay a scientific basis for the environmental management and governance of asbestos polluted sites in China.

Diagnostic limitations of lung fiber counts in asbestos-related diseases

Background Lung dust fibre analyses have been used by some pathologists to estimate past asbestos exposure in the workplace and its related health risks. Asbestos, however, especially the predominately applied chrysotile asbestos type, undergoes translocation, clearance and degradation in the lungs. Objectives We quantified the asbestos fibre and ferruginous (asbestos) body (FB) content in human tissue with respect to the German asbestos ban in 1993 and the interim period of more than 20 years in order to evaluate the diagnostic evidence of these analyses for asbestos-related diseases (ARD). Methods Lung dust analyses have been used in empirical assessments of ARD since 1982. Tissue samples of about 2 cm3 were used and processed in standardized manner. FB was analysed by light microscopy and asbestos fibres by scanning transmission electron microscopy (STEM). Results Chrysotile and amphibole fibre concentrations in the lung tissue depend roughly on the cumulative asbestos exposure levels in the workplace. However, the concentration of lung asbestos fibre and FB depends on the year of examination and especially on the interim period. As the interim period increases, the asbestos fibre burden decreases. There is no relationship between FB and chrysotile asbestos fibre concentrations and only a weak correlation between FB and crocidolite fibre concentrations. There was no significant difference in chrysotile and amphibole fibre concentrations as well as in FB counts between the different ARD. Conclusions Due to the length of interim periods, a past exposure to chrysotile or amphibole asbestos can no longer be detected with FB or asbestos fibre measurement in lung tissue. This means that negative results of such measurements cannot disprove a qualified occupational case history of asbestos exposures and the related health risks due to the fibrogenic and carcinogenic potential of asbestos.

Airborne Asbestos Fiber Concentration in Buildings: Surveys Carried Out in Latium (Central Italy)

In Italy, use and production of asbestos and asbestos-containing materials (ACMs) were banned in 1992, however, the risk of exposure to asbestos still exists, because most ACMs are located in industrial and public buildings. A total of 111 Italian buildings with friable and non-friable ACMs were surveyed; 500 air samples were collected in the areas where contamination might have occurred. Airborne asbestos fiber concentration calculated from air samples was averaged for each building. Statistical analysis of the data showed no significant differences between the mean concentration measured in buildings with friable and non-friable ACMs (p = 0.258). The concentration values were below 2 f/L, the value stated by Italian regulation to ensure that the area is safe to reoccupy after asbestos removal. Samples of settled dust were also collected. The presence of asbestos fibers in the dust showed the occurrence of a release of asbestos from the material. Although the airborne asbestos fiber concentrations measured were low, current Italian regulation requires an asbestos management program. The Public Institution to which the authors of this work belong encourages asbestos removal as the preferred abatement method, in line with the asbestos-free future approach proposed by the European Commission.

JAPANESE EXPERIENCE IN INNOVATIONS APPLICATION IN FRAMES OF ENVIRONMENTAL CONTROL

In the article, in the context of the performed research in Environmental Control Center Co., Ltd, the topic of the environment is touched upon. The history of the formation of the legislative base of ecological monitoring of the environment in Japan is briefly reviewed. Special attention is given to the generalized materials obtained in the framework of the performed research works related to the localization of the methodical approach for determining the content of hexavalent chromium in the environment and the development of an express method for measuring the concentration of asbestos fibers in atmospheric air. An analysis of scientific research is given for each of the listed topics. The article also presents views on the current state of the issue of preventing pollution of the marine environment with plastic. This direction of research is also supplemented by the presentation of national projects operating in Japan. Keywords: environmental protection, methodical approach, measurement method, hexavalent chromium, asbestos fibers, marine plastic, national projects.

Prediction of Asbestos-Related Diseases (ARDs) and Chrysotile Asbestos Exposure Concentrations in Asbestos-Cement (AC) Manufacturing Factories in Zimbabwe.

The use of historical asbestos measurement data in occupational exposure assessment is essential as it allows more quantitative analysis of possible exposure response relationships in asbestos-related disease (ARD) occurrence. The aim of this study was to predict possible ARDs, namely lung cancer, mesothelioma, gastrointestinal cancer, and asbestosis, in two chrysotile asbestos cement (AC) manufacturing factories. Prediction of ARDs was done using a specific designed job-exposure matrix for airborne chrysotile asbestos fibre concentrations obtained from the Harare and Bulawayo AC factories and through application of OSHA's linear dose effect model in which ARDs were estimated through extrapolation at 1, 10, 20, and 25 years of exposure. The results show that more cancer and asbestosis cases are likely to be experienced among those exposed before 2008 as exposure levels and subsequently cumulative exposure were generally much higher than those experienced after 2008. After a possible exposure period of 25 years, overall cancer cases predicted in the Harare factory were 325 cases per 100,000 workers, while for the Bulawayo factory, 347 cancer cases per 100,000 workers exposed may be experienced. Possible high numbers of ARDs are likely to be associated with specific tasks/job titles, e.g., saw cutting, kollergang, fettling table, ground hard waste, and possibly pipe-making operations, as cumulative exposures, though lower than reported in other studies, may present higher risk of health impairment. The study gives insights into possible ARDs, namely lung cancer, mesothelioma, gastrointestinal cancer, and asbestosis, that may be anticipated at various cumulative exposures over 1, 10, 20, and 25 years of exposure in AC manufacturing factories in Zimbabwe. Additionally, results from the study can also form a basis for more in-depth assessment of asbestos cancer morbidity studies in the AC manufacturing industries.

Investigation of asbestos concentration in ambient and lavage fluids of patients referred for bronchoscopy, Ahvaz.

The amount of fibers in the lungs is considered to reflect the cumulative intensity of past asbestos exposure, and bronchoalveolar lavage (BAL) has been proposed to be a good indicator of the presence and quantity of asbestos particles in the lungs. This study evaluated the asbestos concentration in BAL fluids of asbestos-exposed and unexposed pulmonary patients and the environment of Ahvaz city. This prospective study was conducted on 80 patients underwent diagnostic fiberoptic bronchoscopy referred to Imam Khomeini Hospital in Ahvaz, Iran, in 2019. Patients with Lung diseases were divided into three groups based on CT scan results: normal (n = 32), lung cancer (n = 40) and Interstitial lung disease (n = 8). The analysis of asbestos fiber concentration in BAL fluid was carried out by Scanning Electron Microscope (SEM). The positive asbestos test was detected in 69% of all subjects, including 64% of whom had asbestos-related jobs and 74.5% of those with non-related jobs (p = 0.240). The concentrations of asbestos fiber in the BAL in normal patients, lung cancer and interstitial fibrosis (ILD) were 8.13 ± 5.38, 9.66 ± 7.30 and 6.31 ± 1.98 f/ml, respectively (P = 0.492). There was no significant difference between the asbestos levels and exposure history (P = 0.877). The mean concentration of asbestos in the ambient air during the current year was 2.69 ± 0.57 f/ml (2.26-3.70), and the correlation between asbestos levels in BAL and the air was not significant (r = 0.147; P = 0.243). The exposure of different occupational and non-occupational groups to this carcinogenic substance indicates the need for environmental and individual control measures to reduce and prevent asbestos exposure.

NEUTRALISATION OF ASBESTOS-CONTAINING WASTE

Abstract. The paper presents the characteristics of asbestos as a mineral. Asbestos is a trade name for six serpentine fibrous minerals and amphiboles. The processes of removing asbestos-containing products, which poses a high risk of emission of asbestos fibers harmful to human health, is described. First, make an inventory of asbestos-containing waste to determine the sequence of actions. Products can be qualified for immediate disposal or for temporary preservation, as required by law. When removing asbestos-containing products, the contractor should set up warning boards, fence the area, and take technical measures to eliminate the emission of asbestos fibers. Asbestos-containing products must be moistened with water before being removed. Trained employees should be equipped with personal protective equipment as well as working clothes and footwear. Asbestos-containing waste should be taken to a hazardous waste landfill or an inert or other than inert waste landfill, and placed in areas specially adapted for this purpose. Precautions during inventory and liquidation of asbestos-containing waste are specified. An innovative technology for asbestos neutralization MTT (Microwave Thermal Treatment) is characterized. The impact of asbestos products on health is discussed. The most dangerous cases of diseases are asbestosis, pleural and pericardial diseases, as well as lung cancer and mesothelioma. The need for research on the concentration of respirable asbestos fibers in the atmospheric air is emphasized.

FIBERS RESPIRABLE IN THE AIR

Abstract. The paper presents the characteristics of respirable fibers. Respirable fibers are defined as fibers less than 3 μm in diameter, more than 5 μm in length, and a length to thickness ratio of the fiber greater than 3:1. Such dimensions of the fibers allow them to hang in the air and have the ability to travel long distances. Examples of respirable fibers are residues of asbestos products or artificial mineral fibers. The respirable size of the fibers is considered to be a physical carcinogen. The cause of diseases is long-term effects on the respiratory system. Asbestos is assigned a first hazard category. Its permissible concentration limit in the preparation is 0.1% by mass. Exceeding this value requires including this dangerous substance in the classification of any mixture. The need for research on the concentration of respirable asbestos fibers in the atmospheric air is emphasized.

Measuring the Concentrations of Asbestos Fibers in Some Crowded Areas of Baghdad in The Summer of 2020

Aims of this research to determine asbestos fibers levels in surrounding air of some crowded sites of Baghdad city were monitored in summer 2020. Collection of samples was conducted by directing air flow to a mixed cellulose ester membrane filter mounted on an open‑faced filter holder using sniffer a low flow sampling pump, samples of air were collected from five studied areas selected in some heavy traffic areas of Baghdad city, (Al-Bayaa and Al-Shurta tunnel, Al-Jadriya, and Al-Meshin commercial complex, control), then analyzed to determine concentrations of asbestos fibers. Counting of asbestos on the filters was carried out through using both scanning electron microscope SEM and an energy dispersive X‑ray system EDS to count and determine asbestos fibers. The results of this research appeared that the levels of asbestos fibers which recorded minimum value in control site was 0.018±0.001 f/ml and maximum value in Al-Gadriya was 0.121±0.006 f/ml. The concentrations of asbestos fibers in all studied areas were more than standards of world health organization WHO for air was 0.0022 f/ml. This may be because the presence of crowded traffic, occurrence of industries near studied areas. Therefore, effective plans like management of traffic, changing of industrial locations, and products substitution replacement can be effective in reduce concentrations of asbestos fibers. Keywords: Asbestos Fibers, SEM, Crowded Areas, Ambient Air, Summer.

Natural and anthropogenic sources of atmospheric air pollution by asbestos fibers

Introduction. Deposits of various types of asbestos are widespread in the earth’s crust. In these areas there may be a possibility of the atmospheric air pollution by asbestos fibers, especially in the case of industrial development of these deposits or active use by the resident population. The purpose of this study was to assess the possibility of air pollution by amphibole asbestos fibers in the areas of disused flooded quarries in Sverdlovsk region. Materials and methods. 5 samples of atmospheric air, water and soil were taken and analyzed at the territories in Sverdlovsk region where magnesio-arfvedsonite and anthophyllite were extracted in the past years. Results. An extremely high content of free fibers of magnesio-arfvedsonite and anthophyllite (up to 20% of the total weight of the samples) was discovered in the soil samples. The concentrations of asbestos fibers in the water averaged 67∙10 6 f/L and 79∙10 6 f/L, respectively. The average concentrations of respirable amphibole asbestos fibers were 0.06 f/ml and 0.05 f/ml, respectively. Limitations. The paper presents the results of a pilot study of air pollution by fibrous particles, based on which it is not possible to give a full description of the situation, taking into account all possible types of anthropogenic activity in the surveyed areas in different seasons of the year. Conclusion. The results obtained indicate an increased risk of air pollution and water environment contamination by free amphibole asbestos fibers due to their leaching and weathering from rocks, as a result of which disused flooded quarries should be considered as natural and anthropogenic sources of pollution. It is necessary to conduct regular monitoring of the environmental situation at these facilities, as well as to develop measures to prevent the exposure of amphibole asbestos fibers on the population.

Pulmonary Asbestos Fiber Burden Is Related to Patient Survival in Malignant Pleural Mesothelioma

IntroductionMalignant pleural mesothelioma (MPM) is associated with poor prognosis and is strongly associated with occupational asbestos exposure. Given the importance of asbestos exposure in MPM pathogenesis, we retrospectively analyzed the types and concentrations of asbestos fibers within the lung tissues of patients with MPM and investigated their effects on all-cause mortality. MethodsWe formed a national data set of patients with MPM identified from the Finnish Cancer Registry and Statistics Finland. These data were merged with pulmonary asbestos fiber analysis results received from the Finnish Institute of Occupational Health. ResultsWe identified 590 patients with MPM who underwent pulmonary asbestos fiber analysis. The median asbestos concentration within dry lung tissue was 3.20 million fibers/gram (range: 0 − 1700 million fibers/gram). Crocidolite and anthophyllite were the most prevalent asbestos fiber types detected in lung tissue. The multivariable risk of death analyses, where changes over time were accounted for, revealed that total asbestos fiber concentration was associated with increased mortality. Nevertheless, no difference in mortality was noted between different fiber types. ConclusionsOur study revealed that pulmonary fiber concentrations correlated with the manner of asbestos usage. Anthophyllite was identified as the sole fiber in a sizable proportion of cases, supporting its independent role in the pathogenesis of MPM. Our findings suggest that asbestos fiber burden, but not fiber type, may have an impact on the prognosis of MPM.

Assessment of the possibility of air pollution by asbestos fibres during the operation of road surfaces containing stabilizing asbestos-containing additives

Introduction. Using materials containing mineral fibres in road construction requires consideration of the risk of air pollution by fibrous particles. The purpose of the study was to assess the possibility of air pollution by asbestos fibres during the operation of road surfaces containing chrysotile asbestos. Materials and Methods. Nine air samples, three dust samples and one asphalt pavement sample were taken on the federal highway. Results. The concentration of asbestos fibres in the air was below the detection limit of ≤ 0.0001 f/ml. When all nine air samples were examined, no asbestos fibres were found. Two agglomerates and one bundle of chrysotile asbestos fibres were found in all three dust samples, which were most likely a part of the road surface. Most fibres were bound with other particles in a single agglomerate in the asphalt sample. The content of asbestos fibres in all three dust samples was less than 0.1%, and the size of the conglomerates did not fit the definition of “respirable fibres”. Limitations. 1) the assessment of air pollution by asbestos fibres was carried out only at one stage (operation) of the pavement life cycle (from production to disposal); 2) a complete assessment of air pollution on highways by all types of particulate particles was not carried out (only asbestos fibres and other fibrous particles were taken into account). Conclusion. At the time of the study, no atmospheric air pollution by free chrysotile asbestos fibres was detected near the highway; the average concentration for the entire time of sampling, as well as the concentrations in each of the samples, was below the detection limit of the method and amounted to ≤0.0001 f/ml, thereby not exceeding the regulatory indicators provided for both in Russia (Sanitary rules and standards 1.2.3685-21 from 28.01.21) and in Germany (TRGS 519). This study is a single-stage screening study. More research is needed to assess the possibility of air pollution by asbestos fibres throughout the entire life cycle of road surfaces constructed using asbestos-containing stabilizing additives (from production to disposal).

Asbestos dust concentrations and health conditions of workers at asbestos-cement corrugated sheet production manufacturers in Vietnam: a nationwide assessment

This study examined contemporary concentrations of asbestos dust during production and the health conditions of workers at asbestos-cement corrugated sheet production manufacturers in Vietnam. A nationwide survey was conducted on 28 factories (with 206 air samples) and 2459 workers. Asbestos fiber dust and the health status of workers were assessed. Results showed that 108/206 (52.4%) samples had asbestos fiber dust. The average concentration of asbestos fibers was 0.19 ± 0.14 fibers/ml. The percentage of workers with thickened pleural lesions/pleural calcification nodules was low. More studies are needed to evaluate the effectiveness of biomarkers in preventing the onset of lung cancer and mesothelioma in workers.

The concentration and prevalence of asbestos fibres in Christchurch, New Zealand's drinking water supply

Abstract Asbestos cement was a common construction material for water pipes during the twentieth century, as a replacement for metal piping that was vulnerable to corrosion. We report on the presence of asbestos fibres in drinking water supply in Christchurch, New Zealand from ageing asbestos cement reticulated water supply. By sampling the mains water supply via hydrants, 19 of our 20 samples showed long asbestos fibres (>10 μm), with an average concentration 0.9 million fibres per litre (MFL). Short asbestos fibres (>0.5 μm) had an average concentration of 6.2 MFL. Sampling was targeted to pipes from 1930 to the 1960s and there was abundant evidence of fibres being released from pipes of this age. Municipalities cannot continue to rely on ageing asbestos-cement piping, as it appears to be releasing asbestos fibres into drinking water with uncertain health implications, and should prioritise replacing pipes greater than 50 years in age, especially where high water pressures or land disturbance occur, to reduce the risk of water-carried asbestos being released into urban environments, and mitigate any risk of asbestos from ingested contaminated water sources.

Quantitative Assessment of Asbestos Fibers in Normal and Pathological Pleural Tissue-A Scoping Review.

Background: pleural mesothelioma is a rare cancer in the general population, but it is more common in subjects occupationally exposed to asbestos. Studies with asbestos fiber quantification in pleural tissue are scarce: for this reason, we aimed at undertaking a scoping review to summarize the evidence provided by studies in which asbestos fibers were determined by electron microscopy (SEM or TEM) in human pleural tissues, whether normal or pathologic. Materials and methods: A scoping review of articles that quantified asbestos fibers in human pleural tissue (normal or pathologic) by electron microscopy (SEM or TEM), in subjects with asbestos exposure (if any) was performed. Results: The 12 studies selected comprised 137 cases, out of which 142 samples were analyzed. Asbestos fibers were detected in 111 samples (78%) and were below the detectable limit in 31 samples (22%). The concentration of asbestos fibers detected in the positive samples was distributed from as low as 0.01 mfgdt (millions of fibers per gram of dry tissue) up to 240 mfgdt. However, the minimum concentration of fibers overlaps in the three types of tissues (normal pleura, pleural plaque, mesothelioma) in terms of magnitude; therefore, it is not possible to distinguish a definite pattern which differentiates one tissue from the other. Conclusions: The studies included were heterogeneous as to the representativeness of the samples and analytical techniques; the possibility of false negatives must be considered. It would be desirable to systematically search for asbestos fibers to fill the knowledge gap about the presence of asbestos fibers in normal or pathological pleural tissue in order to better understand the development of the different pleural diseases induced by this mineral.

Historical Asbestos Measurements in Denmark-A National Database.

Objectives: Due to the long lag-time for health outcomes, historical asbestos exposure measurements are valuable to support assessments of associated occupational health effects, and also to assess time trends and effects of preventive measures. Methods: Different sources of stored data were collated, assessed and refined to create a harmonized database on historical asbestos fibre concentrations measured in specific work tasks and different industries. The final database contains 9236 asbestos measurements from Danish workplaces collected from 1971 to 1997. Results: The geometric mean of asbestos concentrations in different occupations and tasks ranged from 0.003 to 35 fibres cm−3. Highest concentrations were registered during handling of asbestos products in the construction services during the period 1981–1997. Although all the measured asbestos exposures without the use of respiratory equipment by the worker in the period of 1971–1997 exceeded the current 8-h time-weighted average exposure limit of 0.1 fibres cm−3, the majority of samples collected in the earlier period of 1971 to 1980 did not exceed the exposure limit of 2 fibres cm−3, which was in place at the time. All exposure data obtained from 1980 and onwards were found to be one seventh of the mean fibre concentrations in the previous measurement period. The impact of time shows a clear exponentially decreasing trend-line. Conclusions: Despite limitations in coverage of different occupations and tasks associated with the inventoried historical asbestos measurements, the data are helpful to identify specific work scenarios within an industry, where relatively high asbestos exposure levels may still occur or have occurred from 1971 to 1997.